Jeff Brislane

I think that the guy filming had no idea how to video properly anyway! Terrible footage and i'm not fully convinced it is a tornado but I though the same things about it that Brad mention, probable base rotation and possible anti-cycloninc rotation of the feature.

Just out of interest the first supercell also ended in textbook fashion with a likely bow echo and the region this guy was filming could be a comma/bookend echo region from the bowing outflow dominant stage. I hope i'm not trying to make the situation fit the video though.

Jeff Brislane

Steven, the swirling winds in that video, though impressive and obviously very strong, are by no means indicative of a tornado. For starters winds in a tornado funnel travel in one direction around the funnel and don't chop and change suddenly like this wind does. Funnels on weak tornadoes are typically 50 to 100 metres in width so you'd expect the intense wind to only change direction if the funnel crosses direcetly over the property. What we are seeing in this video are the normal vortices and eddies we see in any wind interacting with the ground only far more intense.

Great video Michael, thanks for sharing - I just sat their gobsmacked! Jimmy, I cant really give any great estimate of wind speed but cant help but recall the outflow from the Sth Dakota squall of June 7 2005 or that downburst we experienced when eating at Pizza Hut on one of the last evenings in the USA in 2006! They were the best displays of sustained straight line winds i've experienced but that QLD effort may well have been even stronger towards the end of the video. Wow.

Certainly some absolutely incredible footage. I'd estimate those winds in the 160km/h vicinity. Very brave of the individuals videoing to continue to do so during that - i'm quite sure they didn't realise the danger they were in at the time.

Significant amounts of debris from wind and flooding is clogging the Brisbane River at the moment and they have suspended all river ferries this weekend due to the danger of them hitting a tree or similar.

Logged

Jeff Brislane

I would go as far as to say that the wind speed was likely gusting to 180km/h, maybe even 200km/h. Sustained wind speed could have been as high as 140 km/h average for ten minutes. Comparable to a Cat 3 cyclone. This could be one of the fastest straight line thunderstorm windspeeds ever witnessed in Australia. Bear in mind that 185 km/h is 100 knts.

I recall a severe wind event recently where Mt. Hotham was trashed by winds that reached 180km/h, I believe, and the damage there was comparable to this event.

I'm pretty sure the Mt Hotham event ticked over the 200km/h mark and I *think* that building codes in the alpine areas of Victoria and NSW are higher than that of Brisbane (given that the alpine areas get 130km/h+ winds comparatively frequently in any given year. Also, Double Island Point scored a 196km/h gust in 2006 from a storm.

Another QLD notable include the Brisbane supercell of January 1985 which produced 185km/h (i think) at Brisbane Airport (and cricketball hail also at the airport).